MOSCOW -- Russian and Chinese conservationists began searching Thursday for signs of the last remaining Amur leopards in Russia's Far East and adjacent Chinese border regions, as part of a triennial census of the nearly extinct cats.

The leopards are one of the most endangered species on Earth, with only around 30 remaining in the wilderness of the Russian Pacific's Primorye region and across the border in China's northeastern provinces, the World Wide Fund for Nature said in a statement.

The animals and their habitat face encroachment from development, poachers, logging and other threats, said Dmitry Pikunov, an ecologist with the Russian Academy of Science.

"The condition and quality of its ecosystem in specific places is changing quickly and unfortunately for these predators not for the best," he said in the statement.

"It remains to be said that places where large predators like the leopard and the tiger can have normal lives practically are gone," he said.

Trackers, hunters and animal biologists will spend two weeks across some 1,930 square miles of snowy taiga forests seeking out tracks to determine how many leopards remain, their gender and their size, the organization said.

The cross-border territory is also home to the endangered Siberian tigers, also known as the Amur, Manchurian or Ussuri tiger. Slightly more than 400 tigers are believed to survive in the wild, victims also of encroaching human settlements as well poachers who want hides and bones for use in traditional Chinese medicine.